Musculoaponeurotic Fibrosarcoma Research Articles

The HIF target MAFF promotes tumor invasion and metastasis through IL11 and STAT3 signaling

Hypoxia plays a critical role in tumor progression including invasion and metastasis. To determine critical genes regulated by hypoxia that promote invasion and metastasis, we screen fifty hypoxia inducible genes for their effects on invasion. In this study, we identify v-maf musculoaponeurotic fibrosarcoma oncogene homolog F (MAFF) as a potent regulator of tumor invasion without affecting cell viability. MAFF expression is elevated in metastatic breast cancer patients and is specifically correlated with hypoxic tumors. Combined ChIP- and RNA-sequencing identifies IL11 as a direct transcriptional target of the heterodimer between MAFF and BACH1, which leads to activation of STAT3 signaling. Inhibition of IL11 results in similar levels of metastatic suppression as inhibition of MAFF. This study demonstrates the oncogenic role of MAFF as an activator of the IL11/STAT3 pathways in breast cancer.

Phthalide derivative CD21 attenuates tissue plasminogen activator-induced hemorrhagic transformation in ischemic stroke by enhancing macrophage scavenger receptor 1-mediated DAMP (peroxiredoxin 1) clearance

BackgroundHemorrhagic transformation (HT) is a critical issue in thrombolytic therapy in acute ischemic stroke. Damage-associated molecular pattern (DAMP)-stimulated sterile neuroinflammation plays a crucial role in the development of thrombolysis-associated HT. Our previous study showed that the phthalide derivative CD21 attenuated neuroinflammation and brain injury in rodent models of ischemic stroke. The present study explored the effects and underlying mechanism of action of CD21 on tissue plasminogen activator (tPA)-induced HT in a mouse model of transient middle cerebral artery occlusion (tMCAO) and cultured primary microglial cells.MethodsThe tMCAO model was induced by 2 h occlusion of the left middle cerebral artery with polylysine-coated sutures in wildtype (WT) mice and macrophage scavenger receptor 1 knockout (MSR1−/−) mice. At the onset of reperfusion, tPA (10 mg/kg) was intravenously administered within 30 min, followed by an intravenous injection of CD21 (13.79 mg/kg/day). Neuropathological changes were detected in mice 3 days after surgery. The effect of CD21 on phagocytosis of the DAMP peroxiredoxin 1 (Prx1) in lysosomes was observed in cultured primary microglial cells from brain tissues of WT and MSR1−/− mice.ResultsSeventy-two hours after brain ischemia, CD21 significantly attenuated neurobehavioral dysfunction and infarct volume. The tPA-infused group exhibited more severe brain dysfunction and hemorrhage. Compared with tPA alone, combined treatment with tPA and CD21 significantly attenuated ischemic brain injury and hemorrhage. Combined treatment significantly decreased Evans blue extravasation, matrix metalloproteinase 9 expression and activity, extracellular Prx1 content, proinflammatory cytokine mRNA levels, glial cells, and Toll-like receptor 4 (TLR4)/nuclear factor κB (NF-κB) pathway activation and increased the expression of tight junction proteins (zonula occludens-1 and claudin-5), V-maf musculoaponeurotic fibrosarcoma oncogene homolog B, and MSR1. MSR1 knockout significantly abolished the protective effect of CD21 against tPA-induced HT in tMCAO mice. Moreover, the CD21-induced phagocytosis of Prx1 was MSR1-dependent in cultured primary microglial cells from WT and MSR1−/− mice, respectively.ConclusionThe phthalide derivative CD21 attenuated tPA-induced HT in acute ischemic stroke by promoting MSR1-induced DAMP (Prx1) clearance and inhibition of the TLR4/NF-κB pathway and neuroinflammation.

Radiation inducible MafB gene is required for thymic regeneration

The thymus facilitates mature T cell production by providing a suitable stromal microenvironment. This microenvironment is impaired by radiation and aging which lead to immune system disturbances known as thymic involution. Young adult thymus shows thymic recovery after such involution. Although various genes have been reported for thymocytes and thymic epithelial cells in such processes, the roles of stromal transcription factors in these remain incompletely understood. MafB (v-maf musculoaponeurotic fibrosarcoma oncogene homolog B) is a transcription factor expressed in thymic stroma and its expression was induced a day after radiation exposure. Hence, the roles of mesenchymal MafB in the process of thymic regeneration offers an intriguing research topic also for radiation biology. The current study investigated whether MafB plays roles in the adult thymus. MafB/green fluorescent protein knock-in mutant (MafB+/GFP) mice showed impaired thymic regeneration after the sublethal irradiation, judged by reduced thymus size, total thymocyte number and medullary complexity. Furthermore, IL4 was induced after irradiation and such induction was reduced in mutant mice. The mutants also displayed signs of accelerated age-related thymic involution. Altogether, these results suggest possible functions of MafB in the processes of thymic recovery after irradiation, and maintenance during aging.

MAFG-driven osteosarcoma cell progression is inhibited by a novel miRNA miR-4660

Osteosarcoma (OS) is the most common primary bone malignancy in the adolescent population. MAFG (v-maf avian musculoaponeurotic fibrosarcoma oncogene homolog G) forms a heterodimer with Nrf2 (NF-E2-related factor 2), binding to antioxidant response element (ARE), which is required for Nrf2 signaling activation. We found that MAFG mRNA and protein expression is significantly elevated in human OS tissues as well as in established and primary human OS cells. In human OS cells, MAGF silencing or knockout (KO) largely inhibited OS cell growth, proliferation, and migration, simultaneously inducing oxidative injury and apoptosis activation. Conversely, ectopic overexpression of MAFG augmented OS cell progression in vitro. MicroRNA-4660 (miR-4660) directly binds the 3′ untranslated region (UTR) of MAFG mRNA in the cytoplasm of OS cells. MAFG 3′ UTR luciferase activity and expression as well as OS cell growth were largely inhibited with forced miR-4660 overexpression but augmented with miR-4660 inhibition. In vivo, MAGF short hairpin RNA (shRNA) or forced overexpression of miR-4660 inhibited subcutaneous OS xenograft growth in severe combined immunodeficient mice. Furthermore, MAFG silencing or miR-4660 overexpression inhibited OS xenograft in situ growth in proximal tibia of the nude mice. In summary, MAFG overexpression-driven OS cell progression is inhibited by miR-4660. The miR-4660-MAFG axis could be novel therapeutic target for human OS.

Combined Treatment with Bone Marrow-Derived Mesenchymal Stem Cells and Exendin-4 Promotes Islet Regeneration in Streptozotocin-Induced Diabetic Rats.

This study was designed to assess whether the combination of the glucagon-like peptide-1 (GLP-1) analog exendin-4 (Ex4) and bone marrow-derived mesenchymal stem cell (BM-MSC) could enhance β-cell action in streptozotocin (STZ)-induced diabetic rats. Forty male Sprague-Dawley rats were randomly assigned to five groups: the normal control group (Normal), diabetes mellitus (DM) group, MSC-treated group (MSC), Ex4-treated group (Ex4), and MSC plus Ex4-treated group (MSC+Ex4). Body weight, blood glucose level, intraperitoneal glucose tolerance test, and in vitro glucose-stimulated insulin secretion were used to assess the treatment efficacy. The expression level of insulin, glucagon, pancreatic duodenal homeobox-1 (PDX-1), v-maf musculoaponeurotic fibrosarcoma oncogene homolog A (MafA), glucagon-like peptide-1 receptor (GLP-1R), and forkhead transcription factor 1 (FoxO1) was estimated by immunofluorescence analysis. Proliferation was assessed by Ki67 staining, and apoptosis was determined by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining in β-cells. Glucose-induced insulin secretion in the MSC+Ex4 group was significantly increased compared to that in the MSC group in vitro and in vivo. Compared to that of the other groups, the number of insulin-immunopositive cells was increased in both the MSC and MSC+Ex4 groups. However, β-cell proliferation and apoptosis in the MSC group and MSC+Ex4 group were not significantly different. Importantly, the expression level of PDX-1, MafA, FoxO1, and GLP-1R in β-cells in the MSC+Ex4 group was significantly higher than those in the MSC group. The numbers of insulin+ glucagon+ double positive cells and glucagon+ GLP-1+ double positive cells were significantly increased after MSC treatment and MSC+Ex4 combined treatment, suggesting the enhanced function of newly formed islet β-cells. Our findings showed that the combination of MSC and Ex4 enhanced the function of newly formed β-cells in STZ-induced diabetic rats by acting on multiple insulin transcription factors. Thus, combined MSC and Ex4 therapy provides a feasible approach for future diabetes treatments.

MitoQ protects against hyperpermeability of endothelium barrier in acute lung injury via a Nrf2-dependent mechanism

Recently, numerous evidence has revealed that excessive reactive oxygen species (ROS) production and mitochondrial disruption during acute lung injury (ALI) and its most severe form, acute respiratory distress syndrome (ARDS) will aggravate the inflammatory process. To identify whether antioxidation can be one of the treatment strategies during this progress, we chose mitoQ, a mitochondria-targeted antioxidant that was proved to be effective in reducing ROS generated in mitochondria, as a ROS scavenger to investigate the role of antioxidation in ALI. We demonstrated that overoxidation occurred during the process of ALI, which could be reduced by mitoQ. In the meantime, apoptosis of endothelial cells of ALI mice, accompanied by hyperpermeability of pulmonary vascular and impaired pulmonary function, was partially reversed following an intraperitoneal injection of mitoQ. Moreover, in in vitro study, lipopolysaccharides (LPS) induced excessive ROS production, mitochondrial dysfunction and apoptosis in human pulmonary microvascular endothelial cells (HPMECs), which were rectified by mitoQ. To explore underlying mechanisms, we proceeded RNA-sequencing and found significantly upregulated expression of musculoaponeurotic fibrosarcoma F (MafF) in mitoQ treated group. Additionally, mitoQ inhibited the degradation and increased nuclear translocation of NF-E2-related factor 2 (Nrf2) and upregulated its downstream antioxidant response elements (AREs), such as heme oxygenase (HO)-1 and NAD(P)H:quinone oxidoreductase (NQO)-1. This effect was abolished by transfecting HPMECs with Nrf2 or Maff siRNA. In Nrf2 deficient mice, the protective effects of mitoQ on LPS model of ALI were largely vanished. Taken together, these results provide insights into how antioxidation exerts beneficial effects on ALI via maintaining mitochondrial hemostasis, inhibiting endothelial cells apoptosis, attenuating the endothelial disruption and regulating lung inflammation via Nrf2-MafF/ARE pathway.

P43, a Truncated Form of Thyroid Hormone Receptor α, Regulates Maturation of Pancreatic β Cells.

P43 is a truncated form of thyroid hormone receptor α localized in mitochondria, which stimulates mitochondrial respiratory chain activity. Previously, we showed that deletion of p43 led to reduction of pancreatic islet density and a loss of glucose-stimulated insulin secretion in adult mice. The present study was designed to determine whether p43 was involved in the processes of β cell development and maturation. We used neonatal, juvenile, and adult p43-/- mice, and we analyzed the development of β cells in the pancreas. Here, we show that p43 deletion affected only slightly β cell proliferation during the postnatal period. However, we found a dramatic fall in p43-/- mice of MafA expression (V-Maf Avian Musculoaponeurotic Fibrosarcoma Oncogene Homolog A), a key transcription factor of beta-cell maturation. Analysis of the expression of antioxidant enzymes in pancreatic islet and 4-hydroxynonenal (4-HNE) (a specific marker of lipid peroxidation) staining revealed that oxidative stress occurred in mice lacking p43. Lastly, administration of antioxidants cocktail to p43-/- pregnant mice restored a normal islet density but failed to ensure an insulin secretion in response to glucose. Our findings demonstrated that p43 drives the maturation of β cells via its induction of transcription factor MafA during the critical postnatal window.

C-Fos is upregulated in the genital tubercle of DEHP-induced hypospadiac rats and the prepuce of patients with hypospadias

ABSTRACT This study aimed to investigate the expression of Fos proto-oncogene, AP-1 transcription factor subunit (c-Fos) in the genital tubercle (GT) of rats with di(2-ethylhexyl) phthalate (DEHP)-induced hypospadias and in the prepuce of patients with hypospadias compared with unaffected controls. Pregnant rats were given 750 mg/kg/day DEHP orally from gestational days 12–19. Western blotting showed that c-Fos expression was increased in DEHP-induced hypospadiac male offspring. In addition, 30 prepuce tissue specimens obtained during hypospadias repair surgery were divided into 2 groups: the mild hypospadias group (n = 15) and the severe hypospadias group (n = 15). Fifteen normal prepuce tissue specimens were harvested during elective circumcision as normal controls. Real-time quantitative polymerase chain reaction, western blotting and immunohistochemistry analyses were used to assess c-Fos expression. c-Fos protein levels were higher in the GT of DEHP-induced rats than in that of control rats. c-Fos mRNA and protein levels were also higher in the hypospadias groups than in the control group (p < 0.05, p < 0.001), and c-Fos protein levels were significantly higher in the severe hypospadias group than in the mild hypospadias group (p < 0.01). The expression of c-Fos was increased in both the GT of DEHP-induced hypospadiac rats and the prepuce of hypospadias patients. Thus, c-Fos overexpression might contribute to hypospadias. Abbreviations: DEHP: di(2-ethylhexyl) phthalate; c-Fos: Fos proto-oncogene, AP-1 transcription factor subunit; Mafb: the masculinization-regulatory gene v-maf musculoaponeurotic fibrosarcoma oncogene family, protein B; GT: genital tubercle; ED: embryonic day; AGD: anogenital distance; AGI: anogenital distance index; ED: embryonic day.

The Taming of Nuclear Factor Erythroid-2-Related Factor-2 (Nrf2) Deglycation by Fructosamine-3-Kinase (FN3K)-Inhibitors-A Novel Strategy to Combat Cancers.

Simple SummaryAim of this review is to provide an overview on (a) Fructosamine-3-Kinase (FN3K) and its role in regulating Nuclear Factor Erythorid-2-Related Factor-2 (Nrf2); (b) the role of glycation and deglycation mechanisms in modulating the functional properties of proteins, in particular, the Nrf2; (c) the dual role of Nrf2 in the prevention and treatment of cancers. Since controlling the glycation of Nrf2 is one of the key mechanisms determining the fate of a cell; whether to get transformed into a cancerous one or to stay as a normal one, it is important to regulate Nrf2 and deglycating FN3K using pharmacological agents. Inhibitors of FN3K are being explored currently to modulate Nrf2 activity thereby control the cancers.Glycated stress is mediated by the advanced glycation end products (AGE) and the binding of AGEs to the receptors for advanced glycation end products (RAGEs) in cancer cells. RAGEs are involved in mediating tumorigenesis of multiple cancers through the modulation of several downstream signaling cascades. Glycated stress modulates various signaling pathways that include p38 mitogen-activated protein kinase (p38 MAPK), nuclear factor kappa–B (NF-κB), tumor necrosis factor (TNF)-α, etc., which further foster the uncontrolled proliferation, growth, metastasis, angiogenesis, drug resistance, and evasion of apoptosis in several cancers. In this review, a balanced overview on the role of glycation and deglycation in modulating several signaling cascades that are involved in the progression of cancers was discussed. Further, we have highlighted the functional role of deglycating enzyme fructosamine-3-kinase (FN3K) on Nrf2-driven cancers. The activity of FN3K is attributed to its ability to deglycate Nrf2, a master regulator of oxidative stress in cells. FN3K is a unique protein that mediates deglycation by phosphorylating basic amino acids lysine and arginine in various proteins such as Nrf2. Deglycated Nrf2 is stable and binds to small musculoaponeurotic fibrosarcoma (sMAF) proteins, thereby activating cellular antioxidant mechanisms to protect cells from oxidative stress. This cellular protection offered by Nrf2 activation, in one way, prevents the transformation of a normal cell into a cancer cell; however, in the other way, it helps a cancer cell not only to survive under hypoxic conditions but also, to stay protected from various chemo- and radio-therapeutic treatments. Therefore, the activation of Nrf2 is similar to a double-edged sword and, if not controlled properly, can lead to the development of many solid tumors. Hence, there is a need to develop novel small molecule modulators/phytochemicals that can regulate FN3K activity, thereby maintaining Nrf2 in a controlled activation state.

Responsive Expression of MafF to β-Amyloid-Induced Oxidative Stress.

The small musculoaponeurotic fibrosarcoma (sMaf) proteins MafF, MafG, and MafK are basic region leucine zipper- (bZIP-) type transcription factors and display tissue- or stimulus-specific expression patterns. As the oxidative stress reactive proteins, sMafs are implicated in various neurological disorders. In the present study, the expressions of sMafs were investigated across five databases gathering transcriptomic data from 74 Alzheimer's disease (AD) patients and 66 controls in the Gene Expression Omnibus (GEO) database. The expression of MafF was increased in the hippocampus of AD patients, which was negatively correlated with the expression of the glutamate cysteine ligase catalytic subunit (GCLC). Furthermore, MafF was significantly increased in patients with Braak stage V-VI, compared to those with Braak stage III-IV. β-Amyloid (Aβ), a strong inducer of oxidative stress, plays a crucial role in the pathogenesis of AD. The responsive expressions of sMafs to Aβ-induced oxidative stress were studied in the APP/PS1 mouse model of AD, Aβ intrahippocampal injection rats, and several human cell lines from different tissue origins. This study revealed that only the induction of MafF was accompanied with reduction of GCLC and glutathione (GSH). MafF knockdown suppressed the increase of GSH induced by Aβ. Among sMafs, MafF is the most responsive to Aβ-induced oxidative stress and might potentiate the inhibition of antioxidation. These results provide a better understanding of sMaf modulation in AD and highlight MafF as a potential therapeutic target in AD.

LncRNA TUG1 positively regulates osteoclast differentiation by targeting v-maf musculoaponeurotic fibrosarcoma oncogene homolog B

Osteoclast differentiation-mediates bone resorption is the key biological basis of orthodontic treatment while the specific mechanism of osteoclastogenesis remains unclear. This study aims to explore the underlying mechanism of the osteoclast differentiation from the perspective of long non-coding RNA (LncRNA). In the present study, the osteoclast differentiation of CD14+ peripheral blood mononuclear cells (PBMCs) was induced by recombinant human macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor κB ligand (RANKL), and LncRNA TUG1 expression was dramatically elevated during this process. Functionally, the silence of TUG1 in CD14+ PBMCs decreased tartrate-resistant acid phosphatase (TRAP)-positive cell numbers and the protein levels of TRAP, nuclear factor of activated T cell c1 (NFATc1), and osteoclast-associated receptor (OSCAR), whereas increased V‐maf musculoaponeurotic fibrosarcoma oncogene homolog B (MafB) protein level. The subsequent experiments confirmed that TUG1 lessened the MafB protein level via accelerating its degradation. Then, the interference of MafB reversed the inhibitory effect of si-TUG1 on osteoclastogenesis, including increased the TRAP-positive cell numbers and up-regulated the protein levels of osteoclast markers. Finally, the in vivo experiments displayed that the increased TUG1 levels could promote tooth movement and bone resorption via facilitating osteoclast differentiation in the rat model of orthodontic tooth movement. In summary, TUG1 overexpressed during the process of osteoclast differentiation and positively regulated osteoclast differentiation by targeting MafB.

Association between MAFB rs17820943 and rs6072081 polymorphism and risk of nonsyndromic cleft lip with or without cleft palate: a meta-analysis.

While there have been previous studies examining the relation between the rs17820943 and rs6072081 polymorphisms in the v-maf musculoaponeurotic fibrosarcoma oncogene homolog B (MAFB) gene and rates of nonsyndromic cleft lip with or without cleft palate (NSCL/P), at present the results of these studies have been inconsistent. This meta-analysis therefore aimed to conduct a more robust assessment of the association between the MAFB rs17820943 and rs6072081 polymorphisms and NSCL/P risk. The Embase, Web of Science, PubMed, the China National Knowledge Internet (CNKI), and Wanfang databases were systematically searched to identify relevant studies. In total, five studies incorporating 2769 patients and 2885 controls were identified assessing the rs17820943 polymorphism and three studies incorporating 1242 patients and 1310 controls assessing the rs6072081 polymorphism were identified. This analysis revealed the MAFB rs17820943 and rs6072081 polymorphisms to be linked to a significantly reduced NSCL/P risk (rs17820943: C vs T: OR=0.76, 95% CI=0.70-0.82; CC vs CT: OR=0.75, 95% CI=0.67-0.85; CC vs TT: OR=0.58, 95% CI=0.49-0.67; CC+CT vs TT: OR=0.67, 95% CI=0.59-0.77; CT+TT vs CC: OR=1.43, 95% CI=1.28-1.60; rs6072081: A vs G: OR=0.77, 95%CI=0.68-0.86; AA vs AG: OR=0.76, 95%CI=0.64-0.90; AA vs GG: OR=0.58, 95%CI=0.45-0.74; AA+AG vs GG: OR=0.68, 95%CI=0.54-0.84; AG+GG vs AA: OR=1.40, 95% CI=1.19-1.65). The results of the present meta-analysis indicate that in an East Asian population, for both rs17820943 and rs6072081 were associated with NSCL/P.

Identification of the Nrf2 in the fathead minnow muscle cell line: role for a regulation in response to H2O2 induced the oxidative stress in fish cell.

The Nrf2 (nuclear factor erythroid 2-related factor 2) plays a central role in cell protection against a wide variety of environmental stressors through the Nrf2-Keap1 (Kelch-like ECH-associated protein 1) pathway, but its involvement in modulation of antioxidant system of fish cell is still largely unexplored. The present study focused on the molecular cloning and silencing of the Nrf2 in the fathead minnow muscle cell line (FHM) in response to the oxidative stress induced by H2O2. A full-length cDNA of coding Nrf2 was cloned from FHM cells by RT-PCR and RACE approaches. The obtained cDNA covered 2578bp with an open reading frame (1770bp) of encoding 589 amino acids. Sequence alignment and phylogenetic analysis revealed a high degree of conservation (51-86%) among 16 fishes. Based on the cloned Nrf2 sequence, the siRNA-242 of targeting Nrf2 with the best knocking down efficiency was designed and detected. Then, the mRNA levels of Keap1, Nrf2, Maf (musculoaponeurotic fibrosarcoma oncogene), and HO-1 (haemoxygenase-1); the activities of T-SOD (total superoxide dismutase), CAT (catalase), and GSH-PX (glutathione peroxidase); the levels of GSH (glutathione) and MDA (malonaldehyde); and the cell cycle and apoptosis were analyzed to investigate the molecular responses after H2O2 exposure. These results showed a coordinated transcriptional regulation of Keap1, Maf, and HO-1 and antioxidants (T-SOD, GSH, CAT, and GSH-PX) and MDA levels after H2O2 exposure, leading to oxidative damage and apoptosis. These findings provided an insight to understand the mechanisms of Nrf2 against oxidative stress in fish.

MAFB Promotes Cancer Stemness and Tumorigenesis in Osteosarcoma through a Sox9-Mediated Positive Feedback Loop.

Despite the fact that osteosarcoma is one of the most common primary bone malignancies with poor prognosis, the mechanism behind the pathogenesis of osteosarcoma is only partially known. Here we characterized differentially expressed genes by extensive analysis of several publicly available gene expression profile datasets and identified musculoaponeurotic fibrosarcoma oncogene homolog B (MAFB) as a key transcriptional regulator in osteosarcoma progression. MAFB was highly expressed in tumor tissues and required for proliferation and tumorigenicity of osteosarcoma cells. MAFB expression was elevated in osteosarcoma stem cells to maintain their self-renewal potential in vitro and in vivo through upregulation of stem cell regulator Sox9 at the transcriptional level. Sox9 in turn activated MAFB expression via direct recognition of its sequence binding enrichment motif on the MAFB locus, thereby forming a positive feedback regulatory loop. Sox9-mediated feedback activation of MAFB was pivotal to tumorsphere-forming and tumor-initiating capacities of osteosarcoma stem cells. Moreover, expression of MAFB and Sox9 was highly correlated in osteosarcoma and associated with disease progression. Combined detection of both MAFB and Sox9 represented a promising prognostic biomarker that stratified a subset of patients with osteosarcoma with shortest overall survival. Taken together, these findings reveal a MAFB-Sox9 reciprocal regulatory axis driving cancer stemness and malignancy in osteosarcoma and identify novel molecular targets that might be therapeutically applicable in clinical settings. SIGNIFICANCE: Transcription factors MAFB and Sox9 form a positive feedback loop to maintain cell stemness and tumor growth in vitro and in vivo, revealing a potential target pathway for therapeutic intervention in osteosarcoma.

Momordica balsamina Fruit Extracts Enhances Selected Aspects of the Insulin Synthesis/Secretion Pathway

Previous studies have suggested that crude plant extracts of the anti-diabetic medicinal plant, Momordica balsamina (MB) may exert their anti-diabetic effect through either enhancement of insulin sensitivity or inhibition of intestinal glucose absorption. However, the effects of these MB extracts on insulin synthesis and secretion are not well documented in the literature. Therefore, a main purpose of the current research was to examine in vitro effects of MB crude fruit extracts on selected aspects of the insulin synthesis and secretion pathway. The study results indicated that ethanol, ethyl acetate and hexane MB crude extracts had the significantly enhanced the uptake of glucose by RIN-m5F β-cells in a manner depending on concentration. Furthermore, these same MB fruit extracts significantly increased the quantities of synthesized and secreted insulin by RIN-m5F β-cells. In addition, significant upregulation of the pre-proinsulin gene levels by the same MB fruit extracts was detected by the conventional end-point Polymerase Chain Reaction (RT-PCR), whereas a significant upregulation of gene expression levels of the two pancreatic glucose sensors (glucokinase enzyme and Glucose Transporter 2 (GLUT2)) as well as the two insulin gene transcription factors Musculoaponeurotic Fibrosarcoma homolog A (MafA) and Pancreatic Duodenal Homeobox-1 (PDX-1) were detected by means of quantitative reverse transcriptase PCR. In conclusion, the outcomes of this research propose that MB fruit extracts may, in addition to their effects on sensitivity of insulin and inhibition of intestinal glucose absorption, exert their anti-diabetic effects through stimulation of both the insulin synthesis and secretion.

RBFOX1 Regulates the Permeability of the Blood-Tumor Barrier via the LINC00673/MAFF Pathway

The blood-tumor barrier limits the delivery of therapeutic drugs to brain tumor tissues. Selectively opening the blood-tumor barrier is considered crucial for effective chemotherapy of glioma. RNA-binding proteins have emerged as crucial regulators in various biologic processes. This study found that RNA-binding Fox-1 homolog 1 (RBFOX1) was downregulated in glioma vascular endothelial cells derived from glioma tissues, and in glioma endothelial cells obtained by co-culturing endothelial cells with glioma cells. Overexpression of RBFOX1 impaired the integrity of the blood-tumor barrier and increased its permeability. Additionally, RBFOX1 overexpression decreased the expression of tight junction proteins ZO-1, occludin, and claudin-5. Subsequent analysis of the mechanism indicated that the overexpression of RBFOX1 increased musculoaponeurotic fibrosarcoma protein basic leucine zipper [bZIP] transcription factor F (MAFF) expression by downregulating LINC00673, which stabilized MAFF messenger RNA (mRNA) through Staufen1-mediated mRNA decay. Moreover, MAFF could bind to the promoter region and inhibit the promoter activities of ZO-1, occludin, and claudin-5, which reduced its expression. The combination of RBFOX1 upregulation and LINC00673 downregulation promoted doxorubicin delivery across the blood-tumor barrier, resulting in apoptosis of glioma cells. In conclusion, this study indicated that overexpression of RBFOX1 increased blood-tumor barrier permeability through the LINC00673/MAFF pathway, which might provide a new useful target for future enhancement of blood-tumor barrier permeability.

The Nuclear Remodeling Induced by Helicobacter Cytolethal Distending Toxin Involves MAFB Oncoprotein.

Enterohepatic Helicobacters, such as Helicobacter hepaticus and Helicobacter pullorum, are associated with several intestinal and hepatic diseases. Their main virulence factor is the cytolethal distending toxin (CDT). In the present study, whole genome microarray-based identification of differentially expressed genes was performed in vitro in HT-29 intestinal cells while following the ectopic expression of the active CdtB subunit of H. hepaticus CDT. A CdtB-dependent upregulation of the V-maf musculoaponeurotic fibrosarcoma oncogene homolog B (MAFB) gene encoding the MAFB oncoprotein was found, as well as the CdtB-dependent regulation of several MAFB target genes. The transduction and coculture experiments confirmed MAFB mRNA and protein induction in response to CDT and its CdtB subunit in intestinal and hepatic cell lines. An analysis of MAFB protein subcellular localization revealed a strong nuclear and perinuclear localization in the CdtB-distended nuclei in intestinal and hepatic cells. MAFB was also detected at the cell periphery of the CdtB-induced lamellipodia in some cells. The silencing of MAFB changed the cellular response to CDT with the formation of narrower lamellipodia, a reduction of the increase in nucleus size, and the formation of less γH2AX foci, the biomarker for DNA double-strand breaks. Taken together, these data show that the CDT of enterohepatic Helicobacters modulates the expression of the MAFB oncoprotein, which is translocated in the nucleus and is associated with the remodeling of the nuclei and actin cytoskeleton.

Unraveling the transcriptional determinants of liver sinusoidal endothelial cell specialization.

Liver sinusoidal endothelial cells (LSECs) are the first liver cells to encounter waste macromolecules, pathogens, and toxins in blood. LSECs are highly specialized to mediate the clearance of these substances via endocytic scavenger receptors and are equipped with fenestrae that mediate the passage of macromolecules toward hepatocytes. Although some transcription factors (TFs) are known to play a role in LSEC specialization, information about the specialized LSEC signature and its transcriptional determinants remains incomplete.Based on a comparison of liver, heart, and brain endothelial cells (ECs), we established a 30-gene LSEC signature comprising both established and newly identified markers, including 7 genes encoding TFs. To evaluate the LSEC TF regulatory network, we artificially increased the expression of the 7 LSEC-specific TFs in human umbilical vein ECs. Although Zinc finger E-box-binding protein 2, homeobox B5, Cut-like homolog 2, and transcription factor EC (TCFEC) had limited contributions, musculoaponeurotic fibrosarcoma (C-MAF), GATA binding protein 4 (GATA4), and MEIS homeobox 2 (MEIS2) emerged as stronger inducers of LSEC marker expression. Furthermore, a combination of C-MAF, GATA4, and MEIS2 showed a synergistic effect on the increase of LSEC signature genes, including liver/lymph node-specific ICAM-3 grabbing non-integrin (L-SIGN) (or C-type lectin domain family member M (CLEC4M)), mannose receptor C-Type 1 (MRC1), legumain (LGMN), G protein-coupled receptor 182 (GPR182), Plexin C1 (PLXNC1), and solute carrier organic anion transporter family member 2A1 (SLCO2A1). Accordingly, L-SIGN, MRC1, pro-LGMN, GPR182, PLXNC1, and SLCO2A1 protein levels were elevated by this combined overexpression. Although receptor-mediated endocytosis was not significantly induced by the triple TF combination, it enhanced binding to E2, the hepatitis C virus host-binding protein. We conclude that C-MAF, GATA4, and MEIS2 are important transcriptional regulators of the unique LSEC fingerprint and LSEC interaction with viruses. Additional factors are however required to fully recapitulate the molecular, morphological, and functional LSEC fingerprint.NEW & NOTEWORTHY Liver sinusoidal endothelial cells (LSECs) are the first liver cells to encounter waste macromolecules, pathogens, and toxins in the blood and are highly specialized. Although some transcription factors are known to play a role in LSEC specialization, information about the specialized LSEC signature and its transcriptional determinants remains incomplete. Here, we show that Musculoaponeurotic Fibrosarcoma (C-MAF), GATA binding protein 4 (GATA4), and Meis homeobox 2 (MEIS2) are important transcriptional regulators of the unique LSEC signature and that they affect the interaction of LSECs with viruses.

Nrf2 in adipocytes.

White adipocytes play a key role in maintaining whole body energy homeostasis by forming white adipose tissue (WAT). The impairment of WAT formation or WAT dysfunction is clearly associated with severe metabolic disorders. Mature adipocytes are derived from differentiated preadipocytes and are pivotal in energy storage and metabolism. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a member of a family of CNC-bZIP proteins which exert their transcriptional control on genes harboring antioxidant response elements (ARE) in partnership with small musculoaponeurotic fibrosarcoma proteins. The activation of Nrf2-ARE coordinated by specific repressor Kelch-like ECH-associated protein 1 (Keap1) regulates networks of genes controlling diverse homeostatic processes involving adaptive antioxidant response and detoxification among many other adaptive responses. Interestingly, accumulating evidence indicates that Nrf2 may act as a transcription factor in regulating the formation and function of adipose tissues, including adipogenesis, lipid metabolism and insulin sensitivity. In this mini-review, an overview on the distinct roles of Nrf2 in adipocytes is provided. While highlighting the regulatory role of Nrf2 in adipogenesis, recent key findings on Nrf2 in insulin signal transduction and energy metabolism of adipocytes are also summarized.

HRD1, an Important Player in Pancreatic β-Cell Failure and Therapeutic Target for Type 2 Diabetic Mice.

Inadequate insulin secretion in response to glucose is an important factor for β-cell failure in type 2 diabetes (T2D). Although HMG-CoA reductase degradation 1 (HRD1), a subunit of the endoplasmic reticulum-associated degradation complex, plays a pivotal role in β-cell function, HRD1 elevation in a diabetic setting contributes to β-cell dysfunction. We report in this study the excessive HRD1 expression in islets from humans with T2D and T2D mice. Functional studies reveal that β-cell-specific HRD1 overexpression triggers impaired insulin secretion that will ultimately lead to severe hyperglycemia; by contrast, HRD1 knockdown improves glucose control and response in diabetic models. Proteomic analysis results reveal a large HRD1 interactome, which includes v-maf musculoaponeurotic fibrosarcoma oncogene homolog A (MafA), a master regulator of genes implicated in the maintenance of β-cell function. Furthermore, mechanistic assay results indicate that HRD1 is a novel E3 ubiquitin ligase that targets MafA for ubiquitination and degradation in diabetic β-cells, resulting in cytoplasmic accumulation of MafA and in the reduction of its biological function in the nucleus. Our results not only reveal the pathological importance of excessive HRD1 in β-cell dysfunction but also establish the therapeutic importance of targeting HRD1 in order to prevent MafA loss and suppress the development of T2D.